The present invention relates to an apparatus and a method to reduce restenosis after arterial intervention.
Restenosis after arterial intervention in general, and percutaneous transluminal coronary angioplasty ("PTCA") in particular, is primarily due to medial smooth muscle cell proliferation.
Conventional PTCA is performed using a balloon catheter such an over-the-wire type catheter manufactured, for example, by Scimed Life Systems, Inc, of Maple Grove, Minn. or a mono-rail type catheter manufactured, for example, by Advanced Cardiovascular Systems, Inc, of Temecula, Calif. FIG. 1 depicts such a conventional over-the-wire balloon catheter 1. The conventional balloon catheter 1 is utilized in an angioplasty procedure as follows. A conventional guidewire 2 is inserted into the patient's artery until the distal end of the guidewire 2 is past a target area (not shown) of the artery (not shown) where there is a buildup of material. The conventional balloon catheter 1 has a lumen 3 running therethrough. The guidewire 2 is inserted into the distal end of the balloon catheter 1 and the balloon catheter 1 is advanced over the guidewire until the balloon section 1a of the balloon catheter 1 is adjacent the buildup of material, The balloon section 1a is then inflated by an inflation means (not show) connected to an inflation port 1b to clear the artery. Finally, the balloon section 1a is deflated, the balloon catheter 1 is pulled back up the guidewire and removed and the guidewire is likewise removed from the patient's artery.
Current technology contemplates two distinct design classes for devices for the prevention of restenosis after arterial interventions. The first design class, an arterial stent type device, is designed for long term deployment within the artery. Such a stent, if designed to emit radiation, would be in place long after the time necessary for the prevention of smooth muscle cell proliferation at the arterial site. U.S. Pat. No. 5,059,166 to Fischell describes such a long term stent.
The second design class for restenosis preventing devices contemplates the delivery of unspecified doses of radiation via radioactive catheters and guidewires. These devices utilize a movable, flexible radiation shield. However, it is questionable whether such a radiation shield could be constructed given the thickness of material required to shield the radiation source and the flexibility required to allow delivery of the radiation source and shield to the coronary site. U.S. Pat. No. 5,213,561 to Weinstein relates to a device of this class.
In addition, neither class of devices addresses the need to isolate the radioactive source from contact with the patient's body fluids.